1. Field of the Invention
The present invention relates generally to large capacity storage apparatus, and more particularly to an improved concrete tank structure and methods of constructing same using a plurality of identical concrete wall elements which have high structural integrity for lateral loads.
2. Description of the Prior Art
The use of reinforced concrete tanks for storage of fluids, grains, etc., is well known. Such tanks are desireable because they do not require the constant maintenance and expense characteristic of steel tanks, and because they have a substantially longer life than wood tanks. The various types of concrete tanks known in the prior art are evidenced by the U.S. Pat. Nos. to Ingrahm, 1,001,273; Conzelman, 1,031,050; Laird, 2,414,310; Dobell, 2,932,964; Crown, 3,120,047; Closner, 3,217,451; Pritzker, 3,180,057; and 3,300,916; Alleaume, 3,511,003; Weaver, 3,619,431; Heron, 3,640,038; and Shelander, 3,824,751. Each of these patents discloses a concrete storage tank made by either pouring a formed wall, aligning a series of precast elements into a circular configuration and tying them together, or by wrapping a plurality of steel bands around an otherwise inadequately strengthened tank wall and molding or spraying a concrete coating thereupon. Such tanks are limited in their usefulness in that the poured walls usually cannot sustain high lateral loading, the precast element tanks require intricate connections between the elements and an unduely large amount of reinforcing steel to prevent the elements from separating at their joints and the band reinforced tanks require a large amount of steel banding which makes their construction expensive. Furthermore, all of these types of tanks require some degree of prestressing in order to insure against failure caused by loading forces which will be present when the tanks are filled; this of course further adds to the cost of construction.
A more important disadvantage of the prior art tank structures is that because of the manner of construction they are limited in size. This means that for such applications as dock oil storage applications and the like in which quantities of liquid exceeding a million barrels are stored, a plurality of prior art tanks must be provided thus requiring additional real estate, plumbing, maintenance, etc.